package anzsoft.xmpp4gwt.client;

/**
 * Simple class for Base64 encoding and decoding. Original javascript code was
 * found at http://www.webtoolkit.info/javascript-base64.html .
 * 
 */
public class Base64 {
	@SuppressWarnings("unused")
	private static final String _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

	@SuppressWarnings("unused")
	private static native String _utf8_decode(String utftext) /*-{
		var string = "";
		var i = 0;
		var c = c1 = c2 = 0;

		while ( i < utftext.length ) {
			c = utftext.charCodeAt(i);

			if (c < 128) {
				string += String.fromCharCode(c);
				i++;
			}
			else if((c > 191) && (c < 224)) {
				c2 = utftext.charCodeAt(i+1);
				string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
				i += 2;
			}
			else {
				c2 = utftext.charCodeAt(i+1);
				c3 = utftext.charCodeAt(i+2);
				string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
				i += 3;
			}

		}

		return string;
	}-*/;

	@SuppressWarnings("unused")
	private static native String _utf8_encode(String string) /*-{		
		string = string.replace(/\r\n/g,"\n");
		var utftext = "";

		for (var n = 0; n < string.length; n++) {

			var c = string.charCodeAt(n);

			if (c < 128) {
				utftext += String.fromCharCode(c);
			}
			else if((c > 127) && (c < 2048)) {
				utftext += String.fromCharCode((c >> 6) | 192);
				utftext += String.fromCharCode((c & 63) | 128);
			}
			else {
				utftext += String.fromCharCode((c >> 12) | 224);
				utftext += String.fromCharCode(((c >> 6) & 63) | 128);
				utftext += String.fromCharCode((c & 63) | 128);
			}
		}
	
		return utftext;
	}-*/;

	// public method for decoding
	public static native String decode(String input) /*-{
		var output = "";
		var chr1, chr2, chr3;
		var enc1, enc2, enc3, enc4;
		var i = 0;

		input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

		while (i < input.length) {

			enc1 = @anzsoft.xmpp4gwt.client.Base64::_keyStr.indexOf(input.charAt(i++));
			enc2 = @anzsoft.xmpp4gwt.client.Base64::_keyStr.indexOf(input.charAt(i++));
			enc3 = @anzsoft.xmpp4gwt.client.Base64::_keyStr.indexOf(input.charAt(i++));
			enc4 = @anzsoft.xmpp4gwt.client.Base64::_keyStr.indexOf(input.charAt(i++));

			chr1 = (enc1 << 2) | (enc2 >> 4);
			chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
			chr3 = ((enc3 & 3) << 6) | enc4;

			output = output + String.fromCharCode(chr1);

			if (enc3 != 64) {
				output = output + String.fromCharCode(chr2);
			}
			if (enc4 != 64) {
				output = output + String.fromCharCode(chr3);
			}

		}

		output = @anzsoft.xmpp4gwt.client.Base64::_utf8_decode(Ljava/lang/String;)(output);

		return output;
	}-*/;

	// private method for UTF-8 decoding

	// public method for encoding
	public static native String encode(String input) /*-{
		var output = "";
		var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
		var i = 0;

		input = @anzsoft.xmpp4gwt.client.Base64::_utf8_encode(Ljava/lang/String;)(input);

		while (i < input.length) {
			chr1 = input.charCodeAt(i++);
			chr2 = input.charCodeAt(i++);
			chr3 = input.charCodeAt(i++);

			enc1 = chr1 >> 2;
			enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
			enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
			enc4 = chr3 & 63;

			if (isNaN(chr2)) {
				enc3 = enc4 = 64;
			} else if (isNaN(chr3)) {
				enc4 = 64;
			}

			output = output +
			@anzsoft.xmpp4gwt.client.Base64::_keyStr.charAt(enc1) + @anzsoft.xmpp4gwt.client.Base64::_keyStr.charAt(enc2) +
			@anzsoft.xmpp4gwt.client.Base64::_keyStr.charAt(enc3) + @anzsoft.xmpp4gwt.client.Base64::_keyStr.charAt(enc4);
		}

		return output;
	}-*/;
}
